diff --git a/GPy/kern/_src/add.py b/GPy/kern/_src/add.py
index 3f00b22d..fdebdfac 100644
--- a/GPy/kern/_src/add.py
+++ b/GPy/kern/_src/add.py
@@ -46,9 +46,6 @@ class Add(CombinationKernel):
     def update_gradients_diag(self, dL_dK, X):
         [p.update_gradients_diag(dL_dK, X) for p in self.parts]
 
-    def update_gradients_diag(self, dL_dKdiag, X):
-        [p.update_gradients_diag(dL_dKdiag, X[:,i_s]) for p, i_s in zip(self._parameters_, self.input_slices)]
-
     def gradients_X(self, dL_dK, X, X2=None):
         """Compute the gradient of the objective function with respect to X.